Discovery of (+)-N-(3-aminopropyl)-N-[1-(5-benzyl-3-methyl-4-oxo-[1,2]thiazolo[5,4-d]pyrimidin-6-yl)-2-methylpropyl]-4-methylbenzamide (AZD4877), a kinesin spindle protein inhibitor and potential anticancer agent.

Structure-activity relationship analysis identified (+)-N-(3-aminopropyl)-N-[1-(5-benzyl-3-methyl-4-oxo-[1,2]thiazolo[5,4-d]pyrimidin-6-yl)-2-methylpropyl]-4-methylbenzamide (AZD4877), from a series of novel kinesin spindle protein (KSP) inhibitors, as exhibiting both excellent biochemical potency and pharmaceutical properties suitable for clinical development. The selected compound arrested cells in mitosis leading to the formation of the monopolar spindle phenotype characteristic of KSP inhibition and induction of cellular death. A favorable pharmacokinetic profile and notable in vivo efficacy supported the selection of this compound as a clinical candidate for the treatment of cancer.

The structure-activity relationship of the antimalarial ozonide arterolane (OZ277).

The structure and stereochemistry of the cyclohexane substituents of analogues of arterolane (OZ277) had little effect on potency against Plasmodium falciparum in vitro. Weak base functional groups were not required for high antimalarial potency, but they were essential for high antimalarial efficacy in P. berghei-infected mice. Five new ozonides with antimalarial efficacy and ADME profiles superior or equal to that of arterolane were identified.

Weak base dispiro-1,2,4-trioxolanes: potent antimalarial ozonides.

Thirty weak base 1,2,4-dispiro trioxolanes (secondary ozonides) were synthesized. Amino amide trioxolanes had the best combination of antimalarial and biopharmaceutical properties. Guanidine, aminoxy, and amino acid trioxolanes had poor antimalarial activity. Lipophilic trioxolanes were less stable metabolically than their more polar counterparts.

Antimalarial activity of N-alkyl amine, carboxamide, sulfonamide, and urea derivatives of a dispiro-1,2,4-trioxolane piperidine.

With an aim to identify a dispiro-1,2,4-trioxolane with high oral activity and good physicochemical properties, 27 derivatives of an achiral piperidine trioxolane were synthesized; most were potent antimalarial peroxides with IC(50)s ranging from 0.20 to 7.0 ng/mL. The oral efficacies of two of these were superior to artesunate and comparable to artemether. The attractive chemical simplicity of these compounds is balanced only by an apparent metabolic susceptibility.

Effect of functional group polarity on the antimalarial activity of spiro and dispiro-1,2,4-trioxolanes.

Based on the structures of several lipophilic trioxolane antimalarial prototypes, we set out to determine which functional groups were associated with good antimalarial profiles and identify more polar (lower LogP/LogD) lead compounds with good physicochemical properties. More lipophilic trioxolanes tended to have better oral activities than their more polar counterparts. Trioxolanes with a wide range of neutral and basic, but not acidic, functional groups had good antimalarial profiles.

Identification of an antimalarial synthetic trioxolane drug development candidate.

The discovery of artemisinin more than 30 years ago provided a completely new antimalarial structural prototype; that is, a molecule with a pharmacophoric peroxide bond in a unique 1,2,4-trioxane heterocycle. Available evidence suggests that artemisinin and related peroxidic antimalarial drugs exert their parasiticidal activity subsequent to reductive activation by haem, released as a result of haemoglobin digestion by the malaria-causing parasite. This irreversible redox reaction produces carbon-centred free radicals, leading to alkylation of haem and proteins (enzymes), one of which--the sarcoplasmic-endoplasmic reticulum ATPase PfATP6 (ref. 7)--may be critical to parasite survival. Notably, there is no evidence of drug resistance to any member of the artemisinin family of drugs. The chemotherapy of malaria has benefited greatly from the semi-synthetic artemisinins artemether and artesunate as they rapidly reduce parasite burden, have good therapeutic indices and provide for successful treatment outcomes. However, as a drug class, the artemisinins suffer from chemical (semi-synthetic availability, purity and cost), biopharmaceutical (poor bioavailability and limiting pharmacokinetics) and treatment (non-compliance with long treatment regimens and recrudescence) issues that limit their therapeutic potential. Here we describe how a synthetic peroxide antimalarial drug development candidate was identified in a collaborative drug discovery project.

Cytotoxic analogues of 2,6-bis(arylidene)cyclohexanones.

A series of 2,6-bis(arylidene)cycloalkanones (1) and related compounds containing one or two substituents at the four position of the cyclohexyl ring were prepared and shown to display cytotoxic activity towards murine P388 and L1210 cells as well as human Molt 4/C8 and CEM T-lymphocytes. In some of the series of compounds, positive correlations were noted between the potencies of the enones and the magnitude of the Hammett sigma values of the aryl substituents. Four representative compounds were cytotoxic to a number of human tumours in vitro, particularly towards colon cancer and leukemic cells. A noteworthy feature of the compounds prepared in this study is that, in general, they were well tolerated when administered to rodents. A number of lead molecules emerged from this investigation as well as guidelines for future expansion of these series of compounds.

Immunization to nicotine with a peptide-based vaccine composed of a conformationally biased agonist of C5a as a molecular adjuvant.

This paper describes the synthesis of a nicotine hapten (Nic) that possesses a carboxyl sidearm functional group allowing for conjugation to a peptide via amide bond formation. Nic was attached to the N-terminal amino group of a 19-residue peptide composed of a conformationally biased agonist of human C5a (YSFKPMPLaR), which is used as a molecular adjuvant and a B cell epitope of human MUC1 glycoprotein (YKQGGFLGL) to yield a peptide-based nicotine vaccine, NicYKQGGFLGLYSFKPMPLaR. Rats immunized with this vaccine were significantly less sensitive to behavioral effects (a Pavlovian discrimination task) induced by their exposure to high concentrations of nicotine (0.4 mg/kg) relative to their non-vaccinated counterparts. The attenuation of these nicotine-induced behavioral effects emanated from the presence of nicotine-specific antibodies (Abs) that were present in the sera of vaccinated rats even after their repeated exposure to high concentrations of nicotine during the time required to perform the behavioral assays. These results suggest that immunization with NicYKQGGFLGLYSFKPMPLaR in the absence of adjuvant is an effective means of inducing a nicotine-specific Ab response, which is capable of attenuating nicotine-induced behavioral/psychoactive effects.